A former Democratic National Committee chairman says President Barack Obama and the party’s congressional leaders should immediately come up with a process to identify a potential successor candidate for Hillary Clinton for the off-chance a health emergency forces her out of the race.

“Now is the time for all good political leaders to come to the aid of their party,” said Don Fowler, who helmed the DNC from 1995 to 1997, during Bill Clinton’s presidency, and has backed Hillary Clinton since her 2008 presidential bid. “I think the plan should be developed by 6 o’clock this afternoon.”

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Fowler said he expects Clinton to fully recover from her bout with pneumonia, which forced her to leave a Sept. 11 memorial event early and cancel an early-week fundraising swing. But he said the Democratic Party would be mistaken to proceed without a contingency plan. The party's existing rules empower the DNC to name a replacement candidate but include few guidelines or parameters.

“It’s something you would be a fool not to prepare for,” he said in an interview on Monday. He added a note of caution, should Clinton attempt an expeditious return to the campaign trail.

“She better get well before she gets back out there because if she gets back out there too soon, it might happen again,” he said.

Fowler noted that at one of his first-ever DNC meetings, in 1972, he supported a decision to nominate Sargent Shriver — a member of the Kennedy clan — to replace Thomas Eagleton as George McGovern’s vice presidential nominee, the only time either major party has replaced one of its two national nominees.

Though that transition was relatively seamless, he said, replacing Clinton would be much more acrimonious and could lead to intense lobbying by loyalists to Joe Biden and Bernie Sanders. That’s why, he argued, the party should be prepared.

“This is a different time, with a lot more people who like to express themselves and perhaps wrest control,” he said. “I’m sure some of the Sanders people would want to get into play and some of the Biden people. I think you’re likely to have at least discussions and perhaps controversy.”

The Clinton campaign and DNC did not immediately respond to requests for comment. Interim DNC Chairwoman Donna Brazile said Sunday that she’s glad Clinton appeared to be feeling better and looks forward to “seeing her back out on the campaign trail and continuing on the path to victory.”

Former Pennsylvania Gov. Ed Rendell, who served as general chairman of the DNC during the 2000 election, agreed that the party’s vacancy rules should be modernized, but he said that discussion should wait until after the election.

“There is absolutely no chance Hillary Clinton will withdraw from running for the presidency,” he said in a phone interview.

Rendell, a Clinton surrogate, said he’d battled through three bouts of walking pneumonia in his gubernatorial campaigns and called it a common ailment during grueling bids for office. He added that Clinton is likely to put to rest any concerns about her health when she appears alongside Trump at the debates.

“When Hillary Clinton participates in three debates, stands on her feet for 90 minutes in all of those debates … it will dispel any remaining doubts that any Americans have about her physical fitness to serve,” he said.

Rendell noted that Ronald Reagan appeared unsteady in his first debate against Walter Mondale in 1984, and some speculated about his health at the time. But by the second debate, he had bounced back.

“He performed 100 percent, was at the top of his game,” Rendell recalled, suggesting the second debate erased all memory of his first performance. Reagan went on to win that year in a landslide.

There are still plenty of unknowns about Clinton’s bout with pneumonia, following her near-collapse after leaving Sunday’s Sept. 11 memorial service in New York City. But if her ailment were to persist and prevent Clinton from continuing as a candidate, it would trigger an obscure Democratic Party mechanism that would plunge the presidential race into turmoil.

It’s an extremely unlikely scenario; Clinton’s team says she’ll continue her march toward Election Day later this week. In addition, the campaign plans to make more detailed medical records available soon, a spokesman announced Monday morning.

But just as Trump’s late-summer swoon had Republicans wondering about his ability to continue his campaign, Clinton’s sudden health care scare has skittish Democrats contemplating contingencies as well.

If Clinton could not physically continue her candidacy, she would have to voluntarily cede her nomination, creating a vacancy at the top of the national ticket. If she did, party procedures give the chair of the DNC authority to call a “special meeting” to vote on a replacement nominee. In this case, because chairwoman Debbie Wasserman Schultz resigned in July, her successor, Brazile, has that authority.

“The locus of activity for all of those political questions would then move to the 447 members of the Democratic National Committee,” said Elaine Kamarck, a two-decade veteran of the DNC Rules Committee. “And it’s wide open, and all of the political concern would work out in the context of discussions among the members of the DNC.”

Fowler argued that the party would be wise to immediately set up an even more detailed process for those who might seek to be Clinton’s successor — from a signature-gathering requirement to a process for receiving nominations during the DNC meeting. All of which, he said, would help ensure confidence in the process and lead toward a broad coalescing around a successor candidate.

“There should be a concerted, unified effort on behalf of the president and the Democratic leaders in the House and the Senate and from the officials of the DNC as well — I think unanimity would be absolutely critical,” he said. “The quicker that unanimity develops, the easier and better the process.”

Kamarck noted that the process hasn’t changed in the decades since Eagleton was replaced over mental health concerns. But Fowler said the politics surrounding the top of the ticket would be more intense — and he noted that any change would occur a few weeks later in the campaign season than the switch in 1972. It would likely take two to three weeks to convene the DNC for a special meeting, he said, and intense wrangling could be paralyzing.

Though typically DNC rules permit members to appoint proxies to vote for them if they can’t appear in person, it’s prohibited when voting “to fill a vacancy on the National ticket,” per the party’s bylaws.

Similarly, though only 40 percent of DNC members are typically required to be present at meetings — with another 10 percent voting by proxy — a vote to replace a national nominee requires a majority of the full committee present.

Another challenge: Most states have passed the deadline to change the names of candidates on their ballots, meaning Clinton’s name would likely be required to appear, short of court-ordered solutions or changes in state laws.

Kamarck argues that this issue will be moot because it’s up to members of the Electoral College — typically loyal partisans — to cast formal ballots for president. If a replacement for Clinton were offered, those electors in states won by Democrats would almost certainly cast ballots for the party’s preferred nominee.

Still, Clinton’s campaign is going to great lengths to quash any talk that she won’t fully bounce back.

“I think by the middle of the week she’ll be out there campaigning as aggressively as ever,” Clinton campaign spokesman Brian Fallon said on Monday.

CLARIFICATION: The first sentence has been clarified to reflect that Fowler is calling for a process to identify a potential successor, not that he is calling for that potential successor to be immediately identified.